Gas discharge device



S. RUBEN GAS DISCHARGE DEV ICE Sept.'16, 1941.

Filed April 30, 1940 l N VE N TO R Janine/Fake ATTORN EY Patented Sept. 16, 1941 UNITED STATES PATENT OFFICE GAS DISCHARGE DEVICE Samuel Ruben, New Rochelle, N. Y.

Application April 30, 1940, Serial No. 332,469

9 Claims.

This invention relates to a gas discharge device and specifically to an electric lamp of the fluorescent type capable of directly starting and operating-on' a 120 volt alternating current line without the use of electro-mechanical control inductance voltage boosting means or the use of thermionic emission elements at its terminals to effect local ionization. This application is a continuation in part of my co-pending application bearing Serial Number 212,630, filed June 9, 1938.

To operate a tubular type of gas discharge device of the present art it is necessary to provide at each end of the device means, such as a heated electron emission element, to provide localized ionization, means for disconnecting the heating element once the discharge is started, means to efiect the discharge between the two locally ionized terminals and means for raising the voltage above 120 volts A. C., for example, to 250 volts D. C.

I have found that the same end can be attained in a simple way by employing the principle of voltage doubling through the use of two condensers charged to the peak voltage of the applied alternating current by rectifiers, the condensers being connected in series to effect ignition for starting the discharge through the length of the tube by providing a maximum open circuit potential 01' 350 volts direct current from the 120 volt alternating current circuit. The ignition voltage is provided without resort to any high- 1y inductive element or transformer as is now used.

By the use of rectifier elements preferably of the rod and filament type, a unilateral discharge is effected between the elements of the rectifier couples, thus providing the localized ionization necessary at the tube terminals to establish the glow discharge through the tube, removing the necessity for the independently heated cathode type of terminals and the requirement for a relay device for disconnection after starting. This arrangement thus provides a source of local ionization at each end of the tube and, in combination with the series connected capacitance, a means for raising the potential from 120 volts alternating current to 350 volts direct current, a voltage higher than is necessary to start and maintain the discharge through the entire length of the tube.

While the method and apparatus described is particularly suited to the fluorescent type of tubes, they can be used with any ype of gas discharge tube where a potential greater than comessary in order to start or maintain the discharge.

To more fully describe this device reference is made to the accompanying drawing which 11- lustrates the device structure and the circuit connections, in which The inside wall of glass tube I, is coated with a fluorescent material, such as silicate of zinc, cadmium, berylium or other combinations common to the art. Ateach end of the tube chamber is a glass press 3 and 4 for the support of the various" electrode and lead elements. At 5 and 8 are rod electrodes which, in combination with coiled ring alkaline earth oxide coated tungsten wire electrodes 8 and 12 respectively, and lavite insulations 6 and to, form asimple type of assymetrically conducting electrode assembly. The filament cathodes 8 and I! are made of 2 mil tungsten wire coiled on a 10 mil mandrel, thereafter coated witha mixture of strontium and barium oxides. At I3 is an evacuated glass tube containing mercury and a magnesium strip about A" long, and, mounted within a nickel capsule which, when the tube I, has been completely evacuated, is inductively heated, causing the mercury and the magnesium to volatilize and condense on a lower portion of the walls of tube I. After tube l is heated to about 350 C., evacuated and the metal elements completely degasified as by inductive heating to about 1300" C., a

gas of low ionization potential such as argon or neon or a mixture of the two, or.krypton and zenon or a combination of the two, is admitted into the tube chamber at a pressure at which unilateral conduction at 120 volts A. C. takes place between the rod and filament electrodes of the tube.

rectifier assemblies. Thispressure, which is dependent upon the space between the electrodes, can be in the order of 5 mm. for, an eighteen inch The filament electrodes are coated with a layer of barium, strontium or calcium carbonates mercial alternating current line voltages is necwhich, together with an organic binder which is decomposed along with the reduction of the carbonates to oxides during the inductive heating so as to reduce the work function of the electrodes. At C1 and C: are electrostatic condensers,

and H is a source of commercial voltage such as a volt A. C. line.

The operation of the device is such that when the alternating line potential is applied, a rectified current fiows between the electrodes 5 and 8 which charges half wave the condenser C1 up to a peak value voltage. A similar discharge also occurs between electrodes 8 and I! when the condenser 02 is charged up to peak value, and as both condensers are charged in opposite direchighest voltage points within the tube, at which time, in a tube 18 inches long, with a diameter of about 1 inch, the voltage across the electrodes in the tube drops to about 60 volts at 0.2 amp. when the cathodes are up to thermionic emission temperature. .There are several paths of discharge within the tube once the discharge starts, and as all the current passes through the condensers C1 and C2 they act as limiting reactances avoiding the necessity of any further ballast devices although a series resistance or inductance can be used if desired. Once the discharge is started the effect of the mercury is to assist in the production of ultra-violet radiation when the silicates on the inner walls of the tube fluoresce and give an eflicient light.

In order to obtain a steady discharge with the maximum voltage applied to the condensers the cathode electrodes of the end rectifier assemblies should be of small mass and alkaline oxide coated, so that they will become hot due to energy loss at the electrodes and serve as electron emitters, thus reducing the voltage drop in the end rectifier assemblies. They should be small enough so as to be capable of instantaneous heating to thermionic emission temperatures. If too large, the discharge may be unsteady and localized at a point which continuously shifts.

Furthermore, if too large, the voltage drop in the rectifier is high with reduction in efilciency oi the unit.

The gas pressure best suited for the device will depend upon the length of the tube. With a gas composed of 20% neon, 80% argon, I have found a pressure of 5 mm. with an eighteen inch long tube suitable.

If desired, inductances can be introduced in series with condensers C1 and C2 to bring the circuit into unity power factor. of the inductances can be such as to produce,a resonant circuit and thereby increase the voltage developed across the condensers.

Having described my invention, what I claim as'new and desire to secure by Letters Patent, is:

1. In combination, an electric gaseous discharge device comprising a sealed envelope, a gaseous atmosphere within said envelope, a pair of ionic rectifiers within said envelope each comprising cathode and anode; each of said rectifiers being connected in series with a capacitance and a Also the value 2,255,818 ticns and connectedin series a maximum voltsource of alternating current; a common connection between said capacitances connected to one side of said alternating current source, the

cathode of one rectifier being connected to one of the capacitances and the anode of the other rectifier being connected to the other capacitance.

2. The combination as set out in claim 1, characterized in that the cathode in each rectifier is oxide coated.

3. The combination as set out in claim 1, characterized in that the cathode of each rectifier comprises an alkaline earth oxide member.

4. The combination as set out in claim 1, characterized in that the cathode of each rectifier comprises a tungsten filament.

5. The combination as set out in claim 1, characterized in that the cathode of each rectifier comprises a coiled filament of wire having a diameter not substantially greater than 2 mils.

6. The combination as set out in claim 1, characterized in that the envelope has a deposit of fluorescent material on the inner wall thereof.

7. In combination, an electric gaseous discharge device comprising a sealed envelope, a gaseous atmosphere within said envelope, two diode rectifier assemblies sealed into said envelope, two capacitances in series, the terminal of one of said capacitances being connected to the cathode of one of the rectifiers and a terminal of the other capacitance being connected to the anode of the other rectifier, a source of alternating current, one side of which is connected to the point of common connection between said capacitances, the other side being connected to a common connection between the opposite terminals of each of said rectifier electrodes.

8. In combination, an electric gaseous discharge device comprising a sealed envelope containing a gas of low ionization potential, two rectifiers oppositely disposed within said envelope, each of said rectifiers comprising cathode and anode; two capacitances connected in series by a. common connection or terminal, and a source of alternating current, the common connection or terminal for said capacitances being connected to one side of the alternating current source, the two non-common terminals of saidcapacitances being connected respectively to the cathode and anode of the oppositely disposed rectifiers, the other side of the alternating current source being connected to the other anode and cathode respectively of said rectifiers.

9. The combination as set forth in claim 8, characterized in that the gaseous atmosphere within the envelope also contains mercury.

. SAMUEL RUBEN. 

